package com.atguigu.nio;

import java.io.IOException;
import java.net.InetSocketAddress;
import java.nio.ByteBuffer;
import java.nio.channels.ServerSocketChannel;
import java.nio.channels.SocketChannel;
import java.util.Arrays;

/**
 * Scattering: 将数据写入到buffer时，可以采用buffer数组，依次写入 [分散]
 * Gathering: 从buffer读取数据时，可以采用buffer数组，依次读
 */
public class ScatteringAndGatheringTest {
    public static void main(String[] args) throws IOException {
        //使用 ServerSocketChannel 和 SocketChannel 网络
        ServerSocketChannel serverSocketChannel = ServerSocketChannel.open();
        InetSocketAddress inetSocketAddress = new InetSocketAddress(7000);

        //绑定端口到socket, 并启动
        serverSocketChannel.socket().bind(inetSocketAddress);

        //创建buffer数组
        ByteBuffer[] byteBuffers = new ByteBuffer[2];
        byteBuffers[0] = ByteBuffer.allocate(5);
        byteBuffers[1] = ByteBuffer.allocate(3);

        //等待客户端连接(telnet)
        SocketChannel socketChannel = serverSocketChannel.accept();
        int messageLength = 8;//假定从客户端接收8个字节

        //循环的读取
        while (true){
            int byteRead = 0;
            while (byteRead < messageLength){
                long read = socketChannel.read(byteBuffers);
                byteRead += read;
                System.out.println("byteRead=" + byteRead);
                //使用流打印，看看当前的这个buffer的position 和limit
                Arrays.asList(byteBuffers).stream().map(buffer -> "position=" +
                        buffer.position() + ",limit=" + buffer.limit()).forEach(System.out::println);
            }
            //将所有的buffer 进行flip
            Arrays.asList(byteBuffers).forEach(buffer -> buffer.flip());

            //将数据读出显示到客户端
            long byteWrite = 0;
            while (byteWrite < messageLength){
                long write = socketChannel.write(byteBuffers);
                byteWrite += write;
            }

            //将所有的buffer 进行clear
            Arrays.asList(byteBuffers).forEach(buffer -> buffer.clear());
            System.out.println("byteRead=" + byteRead + ",byteWrite=" + byteWrite + ",messageLength=" + messageLength);
        }
    }
}
